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Lipid knowledge for the personal care industry
Formulating for Stability and Long Shelf-Life
Benjamin Schwartz
Ontario SCC Education Day
September 18, 2018
Formulating for stability and long shelf life
2
Content
Natural emollients
Properties, challenges and possibilities
How to increase stability and keep functionality in naturalformulations
The do’s and don’ts
Rising demand for natural derived emollients
3
Creates challenges for formulators since consumers certainly do not want to
Compromise on aesthetic experience
• visual and sensorial
Sacrifice desired functionality on skin
• moisturising, softening and caring
Pay more for “less” (in terms of perceived quality)
How much oil are we actually talking about?
4
The use of natural oils in cosmetics
Applications with
natural focus
% of oil
typically used
Face Oil up to 100
Body Oil ± 50
Massage Oil ± 50
Lipstick / lipbutter 30-50
Hair oil treatment ±50
Emulsion 10 to 20
And what kind of oils?
Unsaturated oils are often used as the main natural oil!
Name
Sweet Almond
Oil Prunus Amygdalus
Dulcis Oil
Soybean
OilGlycine
Soja Oil
Sunflower
OilHelianthus
Annuus Seed Oil
HO Sunflower
OilHelianthus
Annuus Hybrid Oil
Typical FAC (%):
Palmitic - C16:0 7 10 5 5
Stearic - C18:0 3 4 4 4
Oleic - C18:1 69 23 25 80
Linoleic - C18:2 21 54 63 7
Linolenic - C18:3 1 8 1 1
OSI (110°C) 12 6 6 20
5
And what kind of oils?
Unsaturated oils are often used as the main natural oil!
Name
Sweet Almond
Oil Prunus Amygdalus
Dulcis Oil
Soybean
OilGlycine
Soja Oil
Sunflower
OilHelianthus
Annuus Seed Oil
HO Sunflower
OilHelianthus
Annuus Hybrid Oil
Typical FAC (%):
Palmitic - C16:0 7 10 5 5
Stearic - C18:0 3 4 4 4
Oleic - C18:1 69 23 25 80
Linoleic - C18:2 21 54 63 7
Linolenic - C18:3 1 8 1 1
OSI (110°C) 12 6 6 20
6
And what kind of oils?
Unsaturated oils are often used as the main natural oil!
Name
Sweet Almond
Oil Prunus Amygdalus
Dulcis Oil
Soybean
OilGlycine
Soja Oil
Sunflower
OilHelianthus
Annuus Seed Oil
HO Sunflower
OilHelianthus
Annuus Hybrid Oil
Typical FAC (%):
Palmitic - C16:0 7 10 5 5
Stearic - C18:0 3 4 4 4
Oleic - C18:1 69 23 25 80
Linoleic - C18:2 21 54 63 7
Linolenic - C18:3 1 8 1 1
OSI (110°C) 12 6 6 20
7
Formulating with emollients derived from plants creates challenges
8
Oxidative and hydrolytic stability of the base emollients of high importance
Mineral oils are usually stable against oxidation and hydrolysis
With emollients derived from plants;
• oxidative stability depends on content of polyunsaturated fatty acids and quality
• hydrolytic stability depends on strength of ester bonds and quality
Breakdown of fats – Hydrolysis(presence of water)
9
Changes in product consistency and stability
Triglyceride Diglyceride and free fatty acid
MonoglycerideGlycerol
+ water+ water
+ water
Challenge - pH
10
Recommended pH range is given by the ester bond stability against hydrolysis
Valid for all esters and triglycerides
In general, stable in pH range 4 to 8
Vegetable emollients are suitable for all purpose face care and body care applications
Speciality applications like depilatory products (very low pH), hair straightening (very high pH) should not contain triglyceride or ester based emollients in direct base
If allowed by application, the emollient can be added by the user (ie hair colouring)
Can hydrolysis be prevented?
11
During storage: avoid water and humidity
Keep containers closed and store cool and dry
In the formulation: Avoid strong bases or acids
Keep the pH between 4 – 8
Avoid lipase activity
Typically an effect of microbial contamination
Short-chain triglycerides (coconut/palm kernel oils) are more sensitive than long-chain triglycerides (palm/rapeseed/sheabutter)
Oxidation of unsaturated lipids –Decreasing Shelf Life
12
+ O2
Hydroperoxide
O
H
Volatile aldehyde
O
H
Non volatile aldehyde
Original triglyceride
Oxidation Stability Index
Peroxide Value
Oxidation rate depends on fatty acidcomposition
13
Oxidative stability is dependent on fatty acid composition and antioxidants
14
10 % C18:320% C18:2
Antioxidants added
3% C18:314% C18:2
0 % C18:310% C18:2
0
10
20
30
40
0
10
20
30
40
50
ReferenceCanola Oil
StabilizedCanola Oil
High OleicCanola Oil
High StabilityCanola Oil
mo
nth
s
ho
urs
OSI (hours at 110°C)
Shelf-life (months)
How is the shelf-life affected by oxidation?
15
Oxidation products can be smelly
Volatile, unsaturated aldehydes and hydrocarbons
Odor profile depends on oxidation pathway and starting composition (origin of raw material)
Oxidation products are pro-oxidative
Autocatalysis, increases oxidation rate
Oxidation depletes the content of Omega-3/Omega-6 fatty acids and tocopherols
Loss of skin functionality
Oxidation products can be irritant and/or inflammatory
Free radicals and reactive oxygen species may cause inflammatory reactions and accelerate premature skin aging
Comedogenesis has been linked to oxidation products
What happens during storage? Oxidative breakdown process
Sunflower seed oil stored at 22°C ; OSI (120°C) is 3 hours
16
0 2 4 6 8 10 12
0
50
100
150
200
250
300
Formation of aldehydes and ketones Strong rancid odor and taste.
Formation of polymericTriglycerides thickening
Formation of hydroperoxides rancid odor and
flavor
Pe
roxid
eva
lue
Time (months)
Fatty Acids (%) C16:0 C18:0 C18:1 C18:2 Sunflower Oil 6 4 25 63
Why store cool and dark?
17
Canola oil stored in different conditions
Oxygen and UV-radiation triggers autoxidation of oils and is faster at higher temperature
0
1
2
3
4
5
0 1 2 3 4 5 6 7 8 9 101112
Pero
xid
evalu
e(m
eqO
2/k
g)
Time (months)
+6°C, dark
Room temp, dark
Room temp, light
Influence of temperature and light
0
1
2
3
4
5
6
Start 8 hrs at 40C 8 hrs at 40C + UV
Pe
roxi
de
valu
e(m
eq
O2
/kg)
Stable Oil
Unstable oil
Linear (Stable Oil)
Linear (Unstable oil)
18
Important for many products like day creams / lotions, sun & after sun care products, for all ages and skin types!
Influence of metal ions
0
20
40
60
80
100
Reference Reference + 1.0ppm Fe
Reference + 0.1ppm Cu
Re
lati
ve s
he
lf li
fe (
%)
19
Metal ions induce oxidation and reduce shelf life
AAK Ingredients : <0.5 ppm Fe and <0.05 ppm Cu
Canola oil + 200 ppm alpha-tocopherol
Citric acid (100ppm) helps protection
20
Can I leave a vegetable oil for 1 week in a heating room at 50°C and what will happen to the shelf-life?
1 week at 50C is 168 hrs at 50C ; 168/960 *100 = 17.5 %
leaves 82.5 % at 20C ; 82.5/100 * 7680 hrs = 6336 hrs
Changed total shelf-life to 6504 hrs = 38.7 weeks
±1 wk50C
20C
± 38.7 wks
Liquid Shea(TC) hours weeks110 15100 3090 6080 12070 24060 48050 96040 192030 384020 7680 45.7
Lost 15.4% of shelf-life
NB all values are estimated on original OSI value at 110C and have to be regarded as broad indications only
±45.7 wks
Frequently Asked Question
21
But what about an oil with lower stability? Can I leave a Sunflower Oil for 1 week in a heating room at 50°C? What will happen to the shelf-life?
1 week at 50C is 168 hrs at 50C168/384 *100 = 43.8 %
leaves 56.2% at 20C56.2/100 * 3072 hrs = 1728 hrs
Changed total shelf-life to 1896 hrs = 11.3 weeks
Sunflower oil
(TC) hours weeks
120 3
110 6
100 12
90 24
80 48
70 96
60 192
50 384
40 768
30 1536
20 3072 18.3
NB all values are estimated on original OSI value at 110C and have to be regarded as broad indications only
Lost 38.2% of shelf-life
Frequently Asked Question
Tocopherols – Vitamin E
22
Form R1 R2 R3
Alpha Me Me Me
Beta Me H Me
Gamma H Me Me
Delta H H Me
Potent natural antioxidant and free radical scavengers
Natural vitamin E (d-alpha tocopherol) is a mix of 8 different molecules
Synthetic (dl-alpha tocopherol) is “pure” alpha tocopherol
Tocopherol acetate needs hydrolysis for activation
R3
R1
R2
Mix of natural tocopherol isomers gives prolonged protection
0 10 20 30 40 50 60
0
1000
2000
To
cop
he
rol c
on
ten
t (p
pm
)
Time (Hours)
Alpha
Gamma
Delta
23
Fractionated soybean oil analysed during an OSI experiment at 120°C
Initial protection Second
protection Final protection
Alpha
(mg/kg)
Gamma
(mg/kg)
Delta
(mg/kg)
Soybean oil 10-350 400-2400 150-950
Rapeseed / Canola oil
100-300 300-750 10-20
Maize oil 25-575 270-2470 25-75
Palm oil Tocotrienols
5-185 120-150
5-35 260-300
<70 <70
Sunflower oil 350-700 10-50 1-10
Which tocopherols are present in vegetable oils?
Tocopherol content is determined by plant origin and oil processing
24
Steam distillation
Achieving stability and long shelf life
25
Food grade oils are intended for consumption and not to be put on the skin and exposed to outdoor conditions
Besides oxidation by-products, food grade refined oils may also contain other impurities that cause odour and colour, tolerable in food but not in cosmetics.
Non-refined, cold pressed oils, may contain high content of breakdown products, peroxides and free radicals, proteins, pesticides, metals, coloured components and other environmental impurities influencing the shelf life and functionality.
Conclusion
26
Use refined, deodorised and fresh oils and fats
Avoid mixing old and new batches
Make sure that the raw materials have low contaminant and metal content
Keep pH 4-8
The fatty acid composition in the oil phase is important
Use high stability vegetable oils
Recommended: Linolenic acid content < 1% and/or Linoleic acid content < 10% in the formulation
Combine water-soluble, interfacial and oil soluble antioxidants
Protect against UV, oxygen and high temperatures
Store dark, cold and dry before production
Avoid intense or prolonged heating during production
Use non-transparent packaging of final product